Fix the way MANPATH is set under csh/tcsh

After building and installing openlava-2.2 on a CentOS 6.5 workstation, the error message "Bad : modifier in $ (/)." started appearing at every login with a tcsh shell.

Although this can be corrected by modifying openlava.csh and enclosing the $MANPATH variable in curly braces

```tcsh
    setenv MANPATH ${MANPATH}:/opt/openlava-2.2/share/man
```
it still fails to add the openlava man pages to the path because the MANPATH variable, by default, is not defined at all on login (which in turn causes an "Undefined variable" error after adding the curly braces).

With the fix proposed in this pull request, MANPATH is properly set under csh/tcsh.